Tensile behavior of polypropylene fiber reinforced concrete under uniaxial constant-amplitude cyclic loading: Fatigue properties and probabilistic fatigue life model

An advanced comprehension of tensile fatigue properties is essential in performance design for polypropylene fiber reinforced concrete (PFRC) structures against fatigue loads. This paper conducted a systematic investigation into the tensile fatigue properties of PFRC specimens subject to three stress levels, including the fatigue stress-strain relationship, fatigue strain evolution, fatigue life, and fatigue strength. The results have revealed that the inclusion of polypropylene fiber (PPF) contributes to a remarkable enhancement in the fatigue performance of concrete. Specifically, the life-prolonging effect of PPF becomes more significant when the PFRC specimen is subject to a lower stress level, and its median fatigue strength increases by 157.2 % in contrast to the plain concrete (PC) specimen. In addition, when the stress level increases, the shape of this zone encompassed by the fatigue stress-strain curves of the PFRC specimen gradually transitions from a “short-fat” to a “tall-thin” configuration, demonstrating that the PFRC specimen exhibits a larger ultimate fatigue deformation at a lower stress level. Finally, based on the static tensile strengths of the PFRC specimens, a probabilistic model was developed to predict their fatigue life distribution at an arbitrary stress level. This model offers an accurate prediction, as evidenced by a close agreement with a wide range of test results, presenting its technical feasibility and robustness.